Coordinated Sniper Cohorts on Pump.fun: Detection of 1,012 Persistent Wallet Rings and a Contamination-Adjusted Estimate of Coordination-Specific First-Hour Buyer-Flow Lift

Abstract

Motivated by Kyle (1985) informed order flow and the Meiklejohn et al. (2013) wallet-clustering tradition, we ask whether persistent coordinated wallets causally raise first-hour buyer flow on the Solana pump.fun bonding-curve marketplace. Using 1,578,333 buyer observations from 166,098 launches over 13.4 days (2026-06-11 to 2026-06-25), a two-stage detection pipeline (intra-launch first-buyer-window extraction plus cross-launch persistent-cohort surfacing via union-find on co-occurrence graphs) identifies 1,012 persistent wallet cohorts (2 to 12 wallets, 2,965 addresses) that systematically co-fire as early buyers. Under a contamination-adjusted estimator excluding cohort wallets' own buyer events from the outcome, 1:1 nearest-neighbour propensity-score matching with a 0.2-SD caliper on ten launch-quality covariates (Rosenbaum-Rubin, 1983) yields a first-30-minute buyer-count lift of +16.1% (95% CI [+13.0%, +19.4%]) on 5,419 matched pairs; the corresponding SOL-inflow lift is +6.3% ([-0.5%, +15.1%]), not distinguishable from zero. The naive contaminated same-universe pooled contrast is +130.9%; approximately half is arithmetic contamination from cohort wallets' own buys in the outcome (dropping to +63.9% after cohort exclusion), and most of the remainder is absorbed by PSM on launch-quality covariates. A parallel activity-matched placebo across 100 seeds produces lifts with median +189.6%, above zero and above the real lift in 100/100 seeds, indicating the placebo estimator is biased; we retain it as a bias diagnostic. Of 5,419 treated launches, 382 (7.0%) had zero non-cohort buyers in the first 30 minutes. We release the full cohort catalogue, detection code, PSM script, and robustness artefacts as RED-COHORT-2026-v1 under CC-BY-4.0.